[Synthesis and membrane-dependent processing of a precursor of tick-borne encephalitis virus (flavivirus) structural...

Conditions that permitted cell-free synthesis of at least one of the non-structural, in addition to two-structural, polypeptides of tick-borne encephalitis virus have been found. The time course of accumulation of virus-specific polypeptides in extracts of Krebs-2 cells and reticulocyte lysates as well as the peptide maps of the products synthesised were studied. A model of generation of viral structural polypeptides has been proposed, according to which a common precursor of these proteins while in a nascent form, is processed in a membrane-dependent reaction into a C-terminal segment, corresponding to the polypeptide moiety of envelope glycoprotein E, and an N-terminal segment, doublet p36/33. Subsequently, an N-terminal segment, corresponding to the core polypeptide C, is cleaved off from p36/33. The remaining C-terminal segment of p36/33 is possibly a precursor of the membrane polypeptide M. The translational strategy of flaviviruses is compared to that of other positive-stranded RNA viruses.